Apparatus for fan fold stacking continuous strips of material

ABSTRACT

Apparatus is described for stacking strip material that has been folded in opposite directions, e.g. computer output, by directing sequentially a plurality of fluid jets to position the outfolds of the strip material as it falls into an output receptacle. In particular, the apparatus for stacking includes a plurality of fluid valves located at spaced intervals along a fall plate. A first detector senses the leading edge of the continuous strip material and activates a first timing circuit which controls the energization of a selected fluid valve. A second timing circuit controls the duration of the energization of the fluid valve and a second detector determines the stack height of the strip material in the output receptacle and thereby controls which fluid valve will be energized.

[ 11 3,735,975 [4 1 May 29,1973

United States Patent Sukel et al.

OTHER PUBLICATIONS Pneumatic Stacker; IBM Technical Disclosure Bulletin [54] APPARATUS FOR FAN FOLD STACKING CONTINUOUS STRIPS OF MATERIAL [75] Inventors: Gerald Vol. 13, No. l,June 1970.

J. Sukel; Jacob C. Rubin, both of Rochester, N.Y. Primary Examiner-Robert W. Michell Assistant ExaminerA. Heinz [73] Assignee: Eastman Kodak Company,

Rochester, NY Attorney-W. H. J. Kllne and Douglas L. Hague Apr. 2, 1971 ABSTRACT [22] Filed:

[21] Appl.No.': 130,674

Apparatus is described for stacking strip material that has been folded in opposite directions, e.g. computer 52 us. cl. ....................L270/61 F, 270/69, 270/79,

output, by directing sequentially a plurality of fluid 355/50, 355/64, 355/73 jets to position the outfolds of the strip material as it [51] Int. Cl. 45/00 falls into an output receptacle. In particular, the ap- [58] Field of Search......................270/69, 39, 73, 79,

paratus for stacking includes a plurality of fluid valves located at spaced intervals along a fall plate. A first detector senses the leading edge of the continuous [56] References and strip material and activates a first timing circuit which UNITED STATES PATENTS controls the energization of a selected fluid valve. A second timing circuit controls the duration of the /1971 energization of the fluid valve and a second detector .270/61 F determines the stack height of the strip material in the Reeder et al.

3,586,437 3,423,083 l/l969 Sherrill........... 3,627,304 l2/l97l outputreceptacle and thereby controls which fluid valve will be energized.

FOREIGN PATENTS OR APPLICATIONS 1,214,983 4/1966 Germany............................ 7 Claims, 5 Drawing Figures Patented May 29, 1973 4 Sheets-Sheet l GERALD J. SUKEL JACOB C. RUBIN INVENTORS ATTORNEYS Patented May 29, 1973- 4 Sheets-Sheet 2 FIG. 2

GEFALD J. SUKEL JACOQ BY -M h T TOR IJEYS Patented May 29, 1973 4 Sheets-Sheet 5 FIG. 4

GERALD J. SUKEL ACOB C. RUBIN 'INVEN'IORS 9 341 W 4 SheetsSheet 4 m QI GER'lALD J. SUKEL 1 JACOB C. RUBIN Patented May 29, 1973 mm W Nw $5 m w w J n a one one a u 2 N K o w w 1 J m H L L L 4 I 4 r u II'L FIE F IQ WI ML E APPARATUS FOR FAN FOLD STACKING CONTINUOUS STRIPS OF MATERIAL cRoss REFERENCE To RELATED APPLICATIONS Reference is made to commonly assigned copending US. Patent Application Ser. No. 843,487 entitled Apparatus for Handling Continuous Strips of Material filed y 22, 1969 US 3,627,304) in ject to a significant static charge and/or a high humidity .the'name of Terrence L. Reeder and Albert C. Wiegert.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to apparatus for handling folded, continuous documents and, more particularly, to apparatus for facilitating the stacking of such docu' ments in a fan-folded or zig-zag manner.

2. Description of the Prior Art Fan-folding or zig-zag stacking is utilized in many applications because it provides an efficient method of storing strip material. The stationery used in computers is one application in which an elongated document is stored in a fan-folded or zig-zag manner.

When used in computers or other processing machinery, the elongated paper document is typically fed into the machine from a fan-folded stack, utilized at a work station and then discharged to freely fall into an output receptacle. When a material such as paper is folded or creased to form the document stack, thepaper will be permanently deformed and will retain a memory of the fold even when the paper document is unfolded or extended as it moves through the machine. As the material falls and engages the output receptacle, the weight of the document will, therefore, cause refolding of the document along its crease lines to restack the document in its original fan-folded configuration.

In machines which have a high rate of discharge of the continuous document the free fall method has not proven entirely satisfactory. For example, when such a document is discharged at a high rate from a photographic copying apparatus, typically known as microfilmers, and allowed to free fall into a receptacle, a certain amount of misfolding occurs. Several factors contribute to the misfolding. At high discharge rates there may be more slack in the document between the discharge outlet and the output receptacle than'at slower rates. When this occurs, the edges formed by the folds have a tendency to dive or fall faster than the rest of the document. When the edges of the document reach the stack before the midsection air is trapped between the midsection creating a hump in the stack. Also when diving occurs, a hump may be formed in one end of the stack by an edge which curves back inwardly. At the work station of the machines, as for example the exposure station of a microfllmer, the continuous document is elongated and stretched thereby tending to unbend or flatten the folds in the document. And to the extent that the folded document loses its memory of the folds, it will tend not to restack correctly. The presence of static charges and/or a variable humidity environment also contribute to unreliability in the restacking operation.

One attempt to prevent misfolding has been to provide a mechanical means of refolding the document. However, mechanical refoldinglimits the processing and output speed of the apparatus. Furthermore to be effective, the refolding must occur at a certain distance from the stack and since the height of the stack is continually changing the mechanical folder must be periodically moved either manually or by a complicated linkage mechanism. Improper positioning of the mechanical folder in relation to the stack will, therefore, render the arrangement ineffective to prevent misfolding. In addition, it is desirable to provide the refolding apparatus with means for reliably handling paper subenvironment.

In the above identified copending application Ser. No. 843,487; filed July 22, 1969 (now US. Pat. No. 3,627,304), entitled Apparatus for Handling Continuous Strips of Materials by Reeder and Wiegert and assigned to the assignee of this invention, apparatus is described to facilitate restacking of fan-folded continuous strips of material. More particularly, the apparatus stretches the folds of the continuous document over a hump or raised portion to reinforce their fold memory and further directs the continuous document along a confined path which is abruptly offset to thereby provide a curvature in the continuous document and to eliminate wrinkles in the document which might otherwise serve to reinforce the continuous document along its length or direction of travel thereby preventing the document from bending at its folds.

The present invention provides additional apparatus to further assist in the folding of the document as it restacks in an output receptacle.

SUMMARY OF THE INVENTION It is an object of the present invention to facilitate restacking of a continuous document in a fan-folded configuration.

Another object of the invention is to increase the rate of restacking a fan-folded document.

Another object of the invention is to facilitate the restacking of fan-folded documents of various thicknesses and weights and processed at varying speeds.

Still another object of the invention is to facilitate the restacking of a fan-folded document in high static and humidity environments.

These and other objects are accomplished, according to the preferred embodiment of the invention, by providing a set of fluid jets positioned at spaced intervals along a fall plate of the receptacle disposed to receive the continuous fan-folded document. A sensor is disposed to detect the fold-lines of the document. The sen sor is connected to a'control circuit which'in response to a signal from the sensor selectively connects one of the fluid jets to a controlled pressure fluid supply to direct a series of fluid pulses of a predetermined duration to position one set of folds as the document falls into the receptacle.

In one illustrative embodiment of the invention, the control circuit comprises a detector for determining the stack height of the document in the receptacle, a switching device operative in response to a signal from the detector to selectively couple one of the fluid jets to the pressurized fluid supply and two timing circuits. The first timing circuit allows the document to advance from its sensed position to the correct position for folding, at which time a signal is given to activate the selected fluid jet. The second timing circuit controls the duration of the fluid pulse.

The organization and method of operation of the invention together with further objects and advantages will become more apparent in the detailed description of the preferred embodiment which follows.

BRIEF DESCRIPTION OF THE DRAWINGS In the detailed description of the preferred embodiment presented below, reference is made to the accompanying drawings wherein corresponding parts are identified by like numerals and in which:

FIG. 1 is a perspective view of a microfilmer including a fan-folded stacking apparatus embodying the invention.

FIG. 2 is a sectioned, side view of the photographic apparatus as shown in FIG. 1.

FIG. 3 is an enlarged, sectioned view of a portion of FIG. 2 showing the apparatus for sensing the document folds.

FIG. 4 is an enlarged, sectioned view of a portion of FIG. 2 showing the fluid jets and their sequence of operation.

FIG. 5 is a schematic diagram of the control circuitry used to control the commencement of energization and the length of energization of a selected fluid jet disposed within the apparatus of FIGS. 1, 2 and 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Because photographic apparatus such as microfilmers are well known, the present description will be directed to elements forming part of or cooperating more directly with the present invention, elements not specifically shown or described herein being understood to be selectable from those known in the art.

Referring now to the drawings and in particular to FIGS. 1 and 2, there is shown a photographic copying apparatus including an input or supply tray 11 for receiving a continuous document 12 which is disposed in a zig-zag or fan-folded stack 13. The continuous document 12 is creased at regular intervals so that the document 12 may be disposed as an accordian pleat in the fan-folded stack 13. More particularly, the continuous document has a series of upfolds l4 and a series of downfolds interposed between the upturned folds 14. It should be noted that the upfolds 14 are in an opposite sense to the downfolds 15 so that the document may be folded as shown in FIG. 1. Illustratively, the continuous document 12 may take the form of a computer readout which is to be recorded on microfilm within the photographic copying apparatus 10.

The leading edge of the continuous document 12 is directed from the fan-folded stack 13 upwardly over an entrance flange l7 and along an input or guide shelf 18 to be received between infeed rollers 19 and 20. As shown in FIG. 2, the driven'infeed roller 20 is rotated in a counterclockwise direction to thereby direct the continuous document 12 about the infeed roller 19 into a passageway between a guide plate 28 and a backup plate 30, and through an exposure station 32 formed by a glass flat 34 and an opening within the backup plate 30. As is well known in the art, the information or images carried by the continuous document 12 may be continuously photographed and illuminated through the glass flat 34.

As described in detail in the above identified and commonly assigned application Ser. No. 843,487 (now US Pat. No. 3,627,304, the continuous document l2 is engaged and fed by a pair of main drive rollers 36 and 38 as the document emerges from the exposure station 32. The main drive roller 38 is rotated in a counterclockwise direction as shown in FIG. 2 to direct the continuous document 12 downward and about a raised portion or hump 42 in the path along which the document is directed. The continuous document 12 is further directed downward between a front fall plate 44 and a rear fall plate 46 to be engaged between supplementary drive rollers 49 and 50 which tend to drive the document 12 at a slightly faster speed than the main drive rollers 36 and 38 so that the document is stretched tautly between the two sets of rollers and over the hump 42. As the document is forced around the entrance flange 17, the infeed roller 20 and between the plates 28 and 30, the downfolds 15 are flexed in a sense opposite to their natural crease. The hump 42 serves to flex the folds 15 in an opposite manner to restore the folds to their naturally folded state or direction. Before restacking on the receiving shelf 56, the continuous document 12 is fed through a confined passageway 51 formed between a front guide plate 52 and a lower fall plate 54. An abrupt offset.55 is provided in the confined passageway 51 which forces the document to bend slightly at the folds 14 and 15 as it moves therethrough. This light bend or bias in the downfolds 15 allows the document to be folded easily as it is restacked on the shelf 56. After leaving the confined passageway 51 the document 12 slides down the lower fall plate 54 into a stack 60 upon the inclined and curved receiving shelf 56. The memory of the folds 14 and 15 which helps the continuous document to restack holds the successive portions of the document slightly apart at the folds with the result that the stack 60 of documents is thicker at the fold edges than it is at the center. A depression is created at the center of the stack as the stack grows higher. The curvature of the receiving shelf 56, therefore, has a height equal to the maximum depression of a normally stacked document. Thus as the continuous document 12 continues to stack upon the shelf 56, the depth of the stack 60 increases so that the stack is always pressed firmly against the lower fall plate 54 and the top surface of the stack-60 becomes flatter.

As the continuous document 12 moves between the two sets of rollers 36 and 38 and 49 and 50, means are provided to sense the position of the downfolds 15. In the described embodiment, the means comprises a r'adiation sensitive device such as phototransistor 48 mounted in the rear fall plate 46 and a radiation source 47 mounted in the front fall plate 44 which sense the presence of notches 16 cut into the edge of the document stack 13 comprising the downfolds '15. As best seen in FIG. 3, the phototransistor 48 and the radiation source 47 are arranged and disposed so that the phototransistor is illuminated by the radiation source as each notch 16 passes therebetween. A manifestation of the passage of each of the downfolds 15 as sensed by the phototransistor 48 is coupled to an electronic control circuit which, as will be explained in detail below, performs the dual function of first controlling the energization of a selected fluid jet or valve from a plurality of such jets 45A, B, C and D, after a predetermined time delay and secondly, to control the duration of the energization of the selected fluid jets to position to downfolds 15 of the continuous document 12 as the document falls onto the receiving shelf 56. In some applications notching of the continuous document 12 may be undesirable. In these applications sensing of the downfolds 15 can be accomplished using a counter (not shown) to count the sprocket holes 21 in the continuous document 12 which move past the counter, the counter being pre set so that it gives an output signal only at the sprocket holes which are aligned with the downfolds 15. Alternatively, each of thedownfolds 15 may be marked with a dark spot by drawing a line with a marker along the appropriate edge of the document stack 13. The dark spots are sensed to determine the position of the downfolds 15. The passage of the downfolds can also be sensed without notching by using a mechanical transducer such as a piezoelectric strain gauge. However, photoelectric sensing or the equivalent fluidic-pneumatic sensing is preferred because these sensing techniques involve no physical contact with the document 12 and therefore impose no limitations on the output rate of the photographic copying apparatus 10.

Selection of the particular fluid jet to be energized is determined by-the height of the document stack 60 upon the receiving shelf 56. As shown in FIG. 1, stack height detection is accomplished by a plurality of radiation sensitive devices such as phototransistors 61, 62 and 63 mounted at spaced intervals above receiving shelf 56 in side wall'22 of the photographic copying apparatus and a plurality of radiation sources 64, 65 and 66 correspondingly mounted in opposite side wall 24. As will be explained in detail below, signals from the phototransistors 61, 62'and 63 resulting from the obstruction of the transmission paths to their corresponding radiation sources 64, 65 and 66 respectively, by the increasing height of the document stack 60 are sent to a switching circuit which in response thereto connects the solenoid of one of the jets 45A, 45B, 45C and 45D to a source 26 of low pressure fluid, such as air, supplied through an inlet 27.

'To avoid spurious triggering of the phototransistors 48, 61, 62 and 63 by ambient light, the phototransistors may be of a type sensitive to radiation of a wavelength outside the visible spectrum, such as ultraviolet radiation, which radiation is emitted from the radiation sources 47, 64, 65 and 66. Alternatively, the phototransistors 48, 61, 62 and 63 and the radiation sources 47, 64, 65 and 66 may be enclosed within a light tightchamber.

Positioning of the fluid jets and control of the time of energization and the length of energization of the fluid pulses are critical to proper folding'Control of the fluid pressure is also important. If the pressure is too low, the

fluid flow is not sufficient to blow the document 12 away from the fallplate 54 but, instead, causes Bernoulli effect adhesion to the plate. If the pressure is too high, the fluid pulses will blow the document 12 away from the copying apparatus 10 entirely. In one illustrative example of the invention using a standard l.B.M. continuous document having a thickness of 0.004 inches, a distance of l 1 inches between the folds and a weight about the same'as 12 pound to l4:pound bond paper, proper refolding was achieved by pulsing the selected fluid jet when the downfold 15 is positioned 1 inch above the jet for a duration of 0.06 second at 1.5 P.S.l.

Referring now to FIG. 5 there is shown a control circuit including the'phototransistor 48. Prior to the passage of the leading edge of the continuous document 12 is approximately determined by resistors R1 and R2.

Transistor Q3 is turned off since the only DC connection to its base is returned to ground. With transistor Q3 turned off, its collector goes to the supply voltage keeping transistor Q4 turned off and its collector at ground. Since the base of transistor Q5 is connected to the collector of transistor Q4 through resistor R9, it is also turned off. Transistors Q6, Q7, Q8 and Q9 are cut off for virtually the same reasons as for transistors Q3, Q4 and Q5.

As the leading edge of the document 12 passes between the radiation source 47 and the phototransistor 48, the later goes dark decreasing the base drive to the transistor Q2 and therefore its conduction. This in turn causes the emitter voltage of transistor Q2 to drop allowing the capacitor C2 to begin to discharge through resistors R2 and R3 and capacitor C1 begins to charge to the supply voltage through resistor R1. Diode CR1 at this time is reversed biased and therefore functionally out of the circuit. The remaining portion of the circuit remains stable until the notch 16 in the document 12 passes between the radiation source 47 and the phototransistor 48 illuminating the latenlllumination of the phototransistor 48 turns on transistor Q2 developing a rather large positive pulse across resistor R2 with capacitor C1 acting as the source of voltage for the collector of transistor Q2. The positive pulse at the emitter of transistor O2 is coupled through the capacitor C2 forwardly biasing diode CR1 and driving the base of transistor Q3 positive'thus turning it on. The collector of transistor Q3 now goes negative supplying the base drive to turn on transistor Q4. The collector of transistor Q4 goes to the supply voltage and turns on transistor Q5 through resistor R9. The'collector of transistor 05 becomes negative discharging capacitor C4 through resistors R12, R11 and transistorQS and reverse biasing diode CR3 blocking the signal. When the transistor Q4 was turned on and its collector went to the supply voltage this transition was coupled back through capacitor C3 resistors R7 and R6 to the base of transistor Q3 maintaining it on. It is the on" time of transistor Q3 as determined by a voltage divider network from ground through resistors R5 and R8 to the collector of transistor Q4 that provides the required time delay between the sensing of the notch 16 and the energizing of the selected fluid jet 45A, 45B, 45C, or 45D. The on time of transistor O3 is determined by how long the capacitor C3 can maintain the base drive to transistor Q3 for a given emitter potentialfThe voltage at the emitter of transistor O3 is controlled by the resistor R5 and the adjustable resistor R8. And since the RC charge time for capacitor C3 is a constant as determined by the resistors R6 and R7, the variable time delay is obtained by varying the emitter voltages for transistor Q3. That is to say if the emitter of transistor O3 is made more positive through the adjustment of resistor R8 less time is required for the capacitor C3 to charge to a sufficient level to turn off transistor Q3. Conversely, if the emitter is made more negative, a greater time period is required before capacitor C3 is charged to a sufficient level to turn off transistor Q3. When transistor O3 is i turned off, its collector returns to the supply potential thereby removing the base drive to transistor Q4 turn ing it off. This causes the collectorof transistor O4 to return to ground removing the base drive through resistor R9 to transistor Q5 thus turning it off.

At the time transistor Q5 turns off, its collector goes positive and this transition is coupled through capacitor C4 forwardly biasing diode CR3 and turning on transistor Q6. The turning on of transistor Q6 causes the collector voltage to drop turning on transistor Q7 which in turn provides the base drive to turn on transistor Q8 which in turn provides the base drive to turn on transistor Q9. When the transistor Q9 turns on a positive or high signal is applied to the a terminal of NAND gates 70, 71, 72 and 73 through an inverter 80. And since the transmission paths between the phototransistors 61, 62 and 63 and the radiation sources 64, 65 and 66 respectively, are unobstructed, high signals will also be applied to the b terminal of NAND gate 70 and the c terminals of NAND gates 71 and 72. Low signals will be applied to the b terminals of NAND gates 71, 72 and 73 through inverters 81, 82 and 83. This condition of inputs will energize only the solenoid L1 for fluid jet 45A through NAND gate 70 when transistor Q9 is turned on. The duration of an air pulse is determined by the on time of transistor Q6 as controlled by a voltage divider network from ground through resistors R14 and R17 to the collector of transistor Q7. The on time of transistor Q6 is determined by how long capacitor C5 can maintain the base drive to transistor Q6 with a selected setting of its emitter voltage. The RC charge time for capacitor C5 is a constant as determined by resistors R15 and R16. Thus, resistor R14 and the adjustable resistor R17 which controls the voltage of the emitter of transistor Q6 controls the on" time of transistor Q6 in precisely the same manner as resistor R5 and the adjustable resistor R8 controls the on time of transistor Q3.

The sequential operation of the fluid jets 45A, 45B, 45C and 45D is illustrated in FIG. 4. Initially, the turning on of transistor Q9 activates fluid jet 45A as explained above. Fluid jet 45A continues to be activated by the turning on of transistor Q9 as the document stack 60 increases in height upon the receiving shelf 56 by the distance denoted A in FIG. 4, at which point any further increase in stack height will completely block the transmission path between the phototransistor 61 and the radiation source 64. When phototransistor 61 goes dark a low signal will be applied to terminal b of NAND gate 70 and a high signal will be applied to terminal b of NAND gate 71 turning off solenoid Ll for fluid jet 45A and turning on solenoid L2 for fluid jet 458. Similarly, when the document stack 60 increases in height by the distance B the transmission path be tween the phototransistor 62 and the radiation source 65 will be completely blocked and phototransistor 62 will apply a low signal to the c terminal of NAND, gate 71 and a high signal to the b terminal of NAND gate 72 turning off solenoid L2 for fluid jet 45B and turning on solenoid L3 for fluid jet 45C. When the document stack 60 increases in height by the distance C and the transmission path between the phototransistor 63 and the radiation source 66 is completely blocked, a low signal will be applied to the 0 terminal of NAND gate 72 and a high signal to the b terminal of NAND gate 73 turning off solenoid L3 for fluid jet 45C and turning on solenoid L4 for fluid jet 45D. Capacitors C9, C10 and C11 are coupled in parallel with phototransistors 61,

62 and 63, respectively, so that the momentary darkening of the phototransistors 61, 62 and 63 as the docu- 5 ment 12 falls therepast will not turn the phototransistors off until their transmission paths are completely blocked by the increasing height of the document stack 60. Illustratively, the jets may be spaced at l inch intervals along the vertical center line of the lower fall plate 54; a seven inch document stack 60 would, therefore, require four assist jets.

From the foregoing, the advantages of the present invention are readily apparent. Novel apparatus has been disclosed which positively assists the folding of fanfolded continuous documents without mechanical handling. This is accomplished by directing a series of fluid pulses of controlled duration to position one set of folds as the document restacks upon a receiving member. Reliable stacking of continuous documents can therefore be achieved at high output rates and under variable humidity and electrostatic environments.

The invention has been described in detail with .reference to a preferred embodiment thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. For example, equivalent fluidic-pneumatic devices can be substituted for the electro-mechanical components comprising the two timing circuits and the stack height detection circuit and fluidic means or other means not involving physical contact with the document can be substituted for the described photoelectric fold detectOl'.

We claim:

1. Apparatus for disposing in a stack a continuous document having first and second sets of folds disposed across the width of the document at regular intervals from each other, the first set of folds being creased in a first direction, the second set of folds being creased in a second direction opposite to the first direction, said apparatus comprising:

a. means for receiving the'document stack;

b. means for directing the document along a path into said receiving means;

0. means for directing a-plurality of fluid jets transverse to the path;

d. means for sensing the height of the document stack in said receiving means; and

e. control means responsive to said sensing-means for energizing selected jets of the plurality of jets dependent upon the height ofthe stacked document.

2. Apparatus for stacking a continuous document in a fan-folded configuration, the document having first and second set of folds consecutively interposed between each other, the first and second sets of folds being disposed across the width of the continuous document at regular intervals from each other, the first set of folds being creased in a first direction, the'second set of folds being creased in a second direction opposite the first direction, said apparatus comprising:

a. a receptacle for receiving the document stack;

b. feeding means for advancing the document in an elongated condition along a path and for directing the document in a generally descending manner 65 into said receptacle; 7

c. a plurality of fluid valves positioned transverse to the path;

d. a source of pressurized fluid;

e. means for sensing the height of the document stack in said receptacle and for providing first signals indicative thereof;

f. sensing means for sensing the passage of the folds in the document and for providing second signals indicative thereof; and

g. control means responsive to said first signals for selectively coupling said plurality of valves one at a time to said source of pressurized fluid and responsive to said second signals for energizing said selected valve for a predetermined duration when the document reaches a predetermined position along said path to direct a series of fluid pulses onto successive folds of one of said first and second sets of folds to facilitate the movement and stacking of the document onto said receptacle.

3. Apparatus as claimed in claim 2 in which one set of folds has indicia therein and said sensing means includes: means for sensing said indicia.

4. Apparatus as claimed in claim 3 wherein said control means includes:

a first timing circuit for providing a predetermined time delay between the sensing of said indicia by said sensing means and the energization of said selected valve; and

a second timing circuit for providing a predetermined time delay between the energization of said selected valve and the de-energization of said selected valve.

5. Apparatus as claimed in claim 3 wherein said control means includes:

a switching circuit responsive to said first signals for sequentially coupling said plurality of valves, one at a.time, to said source of pressurized fluid.

6. Apparatus for stacking a continuous document in a fan-folded configuration, the document having first and second sets of folds consecutively interposed between each other, the first and second sets of folds being disposed across the width of the continuous document at regular intervals from each other, the first set of folds being creased in a first direction, the second set of folds havingrindicia and being creased in a second direction opposite the first direction, said apparatus comprising:

a. a receptacle for receiving the document stack;

b. a fall plate;

0. meansfor directing the document along said fall plate and into said receptacle;

d. first and second fluid valves positioned in said fall plate at first and second distances from said receptacle, said first distance being less than said second distance, said fluid valves being disposed to direct fluid pulses transverse to the path of movement of the document along said fall plate;

e. a source of pressurized fluid;

f. means for sensing the height of the document stack in said receptacle and for providing first signals indicative thereof;

g. sensing means for sensing the indicia in the second set of folds; and for providing second signals indicative thereof; and

h. control means responsive to said first signals for sequentially coupling one at a time said first and second fluid valves to said source of pressurized fluid as the height of the stack increases and responsive to said second signals for energizing said coupled fluid valve, said control means including first timing means for providing a first predetermined time delay between the occurrence of said second signals and the energization of said coupled fluid valve to direct a series of fluid pulses onto successive folds of the second set of folds as the docu ment stacks in said receptacle, and a second timing means for deenergizing said coupled valveafter a second predetermined time delay dependent upon the thickness, weight and distance between consecutive folds of the document.

7. Stacking apparatus for use with photographic apparatus having; an input station for receiving a continuous document having a width in a folded configuration, the document having first and second sets of folds consecutively interposed between each other, the first set of folds being creased in a first direction, the second set of folds being creased in a second direction opposite the first direction; an exposure station; an output station; feeding means for advancing the document from the input station through the exposure station in a manner that the document is extended to flex the second set of folds in a sense opposite to the second direction and for directing the document along a path into the output station for restacking in a folded configuration; said stacking apparatus comprising:

a. means for directing a plurality of fluid jets transverse to said path;

b. means for sensing the height of the document stack in said output station and for providing first signals indicative thereof;

c. means positioned at a predetermined position along said path for sensing the passage of the second set of folds in the document ther'epast and for providing second signals indicative thereof; and

d. control means responsive to said first and second signals for sequentially activating selected ones of the plurality of jets for predetermined time intervals to facilitate the stacking of the document in a folded configuration upon said output station. I l 

1. Apparatus for disposing in a stack a continuous document having first and second sets of folds disposed across the width of the document at regular intervals from each other, the first set of folds being creased in a first direction, the second set of folds being creased in a second direction opposite to the first direction, said apparatus comprising: a. means for receiving the dOcument stack; b. means for directing the document along a path into said receiving means; c. means for directing a plurality of fluid jets transverse to the path; d. means for sensing the height of the document stack in said receiving means; and e. control means responsive to said sensing means for energizing selected jets of the plurality of jets dependent upon the height of the stacked document.
 2. Apparatus for stacking a continuous document in a fan-folded configuration, the document having first and second set of folds consecutively interposed between each other, the first and second sets of folds being disposed across the width of the continuous document at regular intervals from each other, the first set of folds being creased in a first direction, the second set of folds being creased in a second direction opposite the first direction, said apparatus comprising: a. a receptacle for receiving the document stack; b. feeding means for advancing the document in an elongated condition along a path and for directing the document in a generally descending manner into said receptacle; c. a plurality of fluid valves positioned transverse to the path; d. a source of pressurized fluid; e. means for sensing the height of the document stack in said receptacle and for providing first signals indicative thereof; f. sensing means for sensing the passage of the folds in the document and for providing second signals indicative thereof; and g. control means responsive to said first signals for selectively coupling said plurality of valves one at a time to said source of pressurized fluid and responsive to said second signals for energizing said selected valve for a predetermined duration when the document reaches a predetermined position along said path to direct a series of fluid pulses onto successive folds of one of said first and second sets of folds to facilitate the movement and stacking of the document onto said receptacle.
 3. Apparatus as claimed in claim 2 in which one set of folds has indicia therein and said sensing means includes: means for sensing said indicia.
 4. Apparatus as claimed in claim 3 wherein said control means includes: a first timing circuit for providing a predetermined time delay between the sensing of said indicia by said sensing means and the energization of said selected valve; and a second timing circuit for providing a predetermined time delay between the energization of said selected valve and the de-energization of said selected valve.
 5. Apparatus as claimed in claim 3 wherein said control means includes: a switching circuit responsive to said first signals for sequentially coupling said plurality of valves, one at a time, to said source of pressurized fluid.
 6. Apparatus for stacking a continuous document in a fan-folded configuration, the document having first and second sets of folds consecutively interposed between each other, the first and second sets of folds being disposed across the width of the continuous document at regular intervals from each other, the first set of folds being creased in a first direction, the second set of folds having indicia and being creased in a second direction opposite the first direction, said apparatus comprising: a. a receptacle for receiving the document stack; b. a fall plate; c. means for directing the document along said fall plate and into said receptacle; d. first and second fluid valves positioned in said fall plate at first and second distances from said receptacle, said first distance being less than said second distance, said fluid valves being disposed to direct fluid pulses transverse to the path of movement of the document along said fall plate; e. a source of pressurized fluid; f. means for sensing the height of the document stack in said receptacle and for providing first signals indicative thereof; g. sensing means for sensing the indicia in the second set of folds; and for proViding second signals indicative thereof; and h. control means responsive to said first signals for sequentially coupling one at a time said first and second fluid valves to said source of pressurized fluid as the height of the stack increases and responsive to said second signals for energizing said coupled fluid valve, said control means including first timing means for providing a first predetermined time delay between the occurrence of said second signals and the energization of said coupled fluid valve to direct a series of fluid pulses onto successive folds of the second set of folds as the document stacks in said receptacle, and a second timing means for deenergizing said coupled valve after a second predetermined time delay dependent upon the thickness, weight and distance between consecutive folds of the document.
 7. Stacking apparatus for use with photographic apparatus having; an input station for receiving a continuous document having a width in a folded configuration, the document having first and second sets of folds consecutively interposed between each other, the first set of folds being creased in a first direction, the second set of folds being creased in a second direction opposite the first direction; an exposure station; an output station; feeding means for advancing the document from the input station through the exposure station in a manner that the document is extended to flex the second set of folds in a sense opposite to the second direction and for directing the document along a path into the output station for restacking in a folded configuration; said stacking apparatus comprising: a. means for directing a plurality of fluid jets transverse to said path; b. means for sensing the height of the document stack in said output station and for providing first signals indicative thereof; c. means positioned at a predetermined position along said path for sensing the passage of the second set of folds in the document therepast and for providing second signals indicative thereof; and d. control means responsive to said first and second signals for sequentially activating selected ones of the plurality of jets for predetermined time intervals to facilitate the stacking of the document in a folded configuration upon said output station. 